Dawei Shang

Protic ionic liquid [Bim][NTf2] with strong hydrogen bond donating ability for highly efficient ammonia absorption

Cost-efficient and environmentally benign treatment of NH3-containing exhaust gas has been a challenge. Ionic liquids (ILs) due to their unique structures and properties are recognized as potential solvents to absorb NH3. In this study, three types of ILs, including [Bmim][NTf2], [Bim][NTf2], [HOOC(CH2)3mim][NTf2], were designed and synthesized with various hydrogen bond donating abilities and characterized based on their thermodynamic dissociation constants (pKa). The results showed that protic ionic liquid (PIL) [Bim][NTf2] with a moderate pKa value had the highest NH3 absorption capacity (up to 2.69 mol NH3 per mol IL, 313 K, 100 kPa). Experimental characterization and theoretical calculations verified that such extremely high NH3 absorption capacity for [Bim][NTf2] resulted from the interactions between H-3 on the imidazole ring and the NH3 molecule and NH3 molecules sintering themselves. Furthermore, stable absorption performance was recorded for [Bim][NTf2] over four cycles, implying potential applications in the industry for NH3 recycling.

Energetic-environmental-economic assessment of the biogas system with three utilization pathways: Combined heat and power, biomethane and fuel cell.

A typical biogas system with three utilization pathways, i.e., biogas upgrading, biogas combined heat and power (CHP), biogas solid oxide fuel cells (SOFCs) were designed. It was assessed from the viewpoint of energy, environment and economy by using energy efficiency, green degree and net present value index respectively. The assessment considered the trade-off relationships among these indexes, which is more comprehensive than previous systematic evaluation work only included single or two of the pathway(s) by using one or two of the index(es). Assessment results indicated that biogas upgrading pathway has the highest systematic energy efficiency (46.5%) and shortest payback period (8.9year) with the green degree production is the lowest (9.29gd/day). While for biogas SOFC pathway, although the green degree production is the highest (21.77gd/day), the payback period is longer (14.5year) and the energy efficiency is 13.6% lower than the biogas upgrading pathway.